Recently, electronic devices such as personal computers and smartphones are equipped with functions of wireless communications and wireless power transmission. In electronic devices, for broadening distance of wireless communication, better efficiency, and a smaller size, a magnetic film for convergence of magnetic flux is disposed around an antenna or coil included in the electronic device (for example, see Patent Document 1).
Patent Document 1 discloses a flexible magnetic film formed by blending flat soft magnetic powder with a binder.
Meanwhile, for improvement in convergence efficiency of magnetic flux, it is important to improve relative magnetic permeability (magnetic properties) of the magnetic film. Generally, increasing the thickness of the magnetic film improves relative magnetic permeability. However, because a small-sized electronic device and furthermore, a thin magnetic film are demanded, it is difficult to meet the demand of a smaller thickness with the above-described method.
Also, increasing the particle size of the magnetic film containing soft magnetic particles can improve relative magnetic permeability (for example, see Patent Document 2).
Patent Document 2 discloses use of a flat soft magnetic material specifying a particle size, a coercive force, and a bulk density for a magnetic sheet.